The invention relates to vaccines suitable for the prophylaxis and control, respectively, of the pig disease caused by Haemophilus pleuropneumoniae as well as to a method for obtaining an extracellular proteinaceous material of Haemophilus pleuropneumoniae, suitable for use in such vaccines.
H. pleuropneumoniae is the causative agent of Haemophilus pleuropneumonia in pigs which at present is regarded as being one of the most important disorders of the bronchial tubes in these animals (see, inter alia, Maudsley J. R. et al. Can. J. Microbiol. 32, (1986), pages 801-805). The principal symptoms in the acute stage of this disease are the occurrence of high fever and an extensive fibrinous hemorrhagic necrotic lobar pneumonia, which is accompanied by fibrinous pleurisy. It is assumed that one or more toxins produced by H. pleuropneumoniae play a significant role in the above pathogenisis. More particularly, it has been observed that endobronchial administration of both sonificated non-viable H. pleuropneumoniae cells and a cell-free supernatant obtained from a culture medium for H. pleuropneumoniae to pigs results in local pneumonia which corresponds to the pneumonia which occurs in experimentally infected pigs. The article by Maudsley J. R. et al, (Can. J. Microbiol. 32, 801-805 (1986)) particularly concentrates on obtaining a hemolysin product produced by H. pleuropneumoniae with the aid of a chemically defined medium (CDM) which does not contain proteins, so that the extracellular hemolysin product obtained with the aid of H. pleuropneumoniae strain 12864 (serotype 3) can be separated off in a relatively simple manner; the product found according to Maudsley et al. appears in experiments to be a heat-labile protein which for the time being, however, cannot be used for vaccination purposes. The said hemolysin product induces hemorrhagic pneumonia in mice.
In "Abstracts of the Annual Meeting of the American Society for Microbiology", Vol. 87, No. 0, 1987, page 40, Summary No. B-91, P. J. Fedorka et al, it is indicated that a hemolytic factor and a cytotoxic factor from H. pleuropneumoniae serotypes 1 and 5 were identified, which factors were heat-labile and pH sensitive. After administration thereof to either pig lung macrophages or mice said factors apparently showed the relevant activity. At the end of this summary it is brought up that isolation of these virulence factors may aid in vaccine development and disease irradiation. However, nothing is mentioned or even suggested therein concerning a universal vaccine which may cope with the majority or even all the serotypes of H. pleuropneumoniae.
Further in "Abstracts of the Annual Meeting of the American Society for Microbiology", Vol. 88, May 8-13, 1988, No. 0, page 35, Summary B-37, P. J. Fedorka et al, it is mentioned that a dialysed hemolysin derived from H. pleuropneumoniae serotype 1 was suitable as the active component of a vaccine. Such a vaccine would provide a marked protection from clinical disease and lung pathology after a challenge with the serotype strain in question. At the end of this summary it is stated that apparently the hemolysin is the major immunogen for protection in the H. pleuropneumoniae induced disease. In this respect, however, it is emphasized that in this last reference nothing is mentioned about the cytotoxic factor of the microorganism in question or the development of a universal vaccine against the many different serotypes of H. pleuropneumoniae.